MyMedR

Fulltext In-silico Taxonomic Classification of 373 Genomes Reveals Species Misidentification and New Genospecies within the Genus Pseudomonas

Tran PN, Savka MA, Gan HM

Front Microbiol, 2017;8:1296.

PMID: 28747902 DOI: 10.3389/fmicb.2017.01296

The genus Pseudomonas has one of the largest diversity of species within the Bacteria kingdom. To date, its taxonomy is still being revised and updated. Due to the non-standardized procedure and ambiguous thresholds at species level, largely based on 16S rRNA gene or conventional biochemical assay, species identification of publicly available Pseudomonas genomes remains questionable. In this study, we performed a large-scale analysis of all Pseudomonas genomes with species designation (excluding the well-defined P. aeruginosa) and re-evaluated their taxonomic assignment via in silico genome-genome hybridization and/or genetic comparison with valid type species. Three-hundred and seventy-three pseudomonad genomes were analyzed and subsequently clustered into 145 distinct genospecies. We detected 207 erroneous labels and corrected 43 to the proper species based on Average Nucleotide Identity Multilocus Sequence Typing (MLST) sequence similarity to the type strain. Surprisingly, more than half of the genomes initially designated as Pseudomonas syringae and Pseudomonas fluorescens should be classified either to a previously described species or to a new genospecies. Notably, high pairwise average nucleotide identity (>95%) indicating species-level similarity was observed between P. synxantha-P. libanensis, P. psychrotolerans-P. oryzihabitans, and P. kilonensis- P. brassicacearum, that were previously differentiated based on conventional biochemical tests and/or genome-genome hybridization techniques.

Fulltext Whole-Genome Sequencing Reveals a New Genospecies of Methylobacterium sp. GXS13, Isolated from Vitis vinifera L. Xylem Sap

Lai WX, Gan HM, Hudson AO, Savka MA

Genome Announc, 2016;4(1).

PMID: 26847900 DOI: 10.1128/genomeA.01695-15

The whole-genome sequence of a new genospecies of Methylobacterium sp., named GXS13 and isolated from grapevine xylem sap, is reported and demonstrates potential for methylotrophy, cytokinin synthesis, and cell wall modification. In addition, biosynthetic gene clusters were identified for cupriachelin, carotenoid, and acyl-homoserine lactone using the antiSMASH server.

Fulltext Improved genome of Agrobacterium radiobacter type strain provides new taxonomic insight into Agrobacterium genomospecies 4

Gan HM, Lee MVL, Savka MA

PeerJ, 2019;7:e6366.

PMID: 30775173 DOI: 10.7717/peerj.6366

The reported Agrobacterium radiobacter DSM 30174T genome is highly fragmented, hindering robust comparative genomics and genome-based taxonomic analysis. We re-sequenced the Agrobacterium radiobacter type strain, generating a dramatically improved genome with high contiguity. In addition, we sequenced the genome of Agrobacterium tumefaciens B6T, enabling for the first time, a proper comparative genomics of these contentious Agrobacterium species. We provide concrete evidence that the previously reported Agrobacterium radiobacter type strain genome (Accession Number: ASXY01) is contaminated which explains its abnormally large genome size and fragmented assembly. We propose that Agrobacterium tumefaciens be reclassified as Agrobacterium radiobacter subsp. tumefaciens and that Agrobacterium radiobacter retains it species status with the proposed name of Agrobacterium radiobacter subsp. radiobacter. This proposal is based, first on the high pairwise genome-scale average nucleotide identity supporting the amalgamation of both Agrobacterium radiobacter and Agrobacterium tumefaciens into a single species. Second, maximum likelihood tree construction based on the concatenated alignment of shared genes (core genes) among related strains indicates that Agrobacterium radiobacter NCPPB3001 is sufficiently divergent from Agrobacterium tumefaciens to propose two independent sub-clades. Third, Agrobacterium tumefaciens demonstrates the genomic potential to synthesize the L configuration of fucose in its lipid polysaccharide, fostering its ability to colonize plant cells more effectively than Agrobacterium radiobacter.

Fulltext Genome sequence of Methylobacterium sp. strain GXF4, a xylem-associated bacterium isolated from Vitis vinifera L. grapevine

Gan HM, Chew TH, Hudson AO, Savka MA

J Bacteriol, 2012 Sep;194(18):5157-8.

PMID: 22933776 DOI: 10.1128/JB.01201-12

Methylobacterium sp. strain GXF4 is an isolate from grapevine. Here we present the sequence, assembly, and annotation of its genome, which may shed light on its role as a grapevine xylem inhabitant. To our knowledge, this is the first genome announcement of a plant xylem-associated strain of the genus Methylobacterium.

Fulltext Genome sequence of Novosphingobium sp. strain Rr 2-17, a nopaline crown gall-associated bacterium isolated from Vitis vinifera L. grapevine

Gan HM, Chew TH, Hudson AO, Savka MA

J Bacteriol, 2012 Sep;194(18):5137-8.

PMID: 22933764 DOI: 10.1128/JB.01159-12

Novosphingobium sp. strain Rr 2-17 is an N-acyl homoserine lactone (AHL)-producing bacterium isolated from the crown gall tumor of a grapevine. To our knowledge, this is the first draft genome announcement of a plant-associated strain from the genus Novosphingobium.

Fulltext High-Quality Draft Genome Sequence of the Type Strain of Allorhizobium vitis, the Primary Causal Agent of Grapevine Crown Gall

Gan HM, Lee MVJ, Savka MA

Microbiol Resour Announc, 2018 Sep;7(9).

PMID: 30533933 DOI: 10.1128/MRA.01045-18

Using Illumina and Nanopore reads, we assembled a high-quality draft genome sequence of Allorhizobium vitis K309T (= ATCC 49767T, = NCPPB 3554T), a phytopathogenic strain isolated from a grapevine in Australia. The hybrid approach generated 50% fewer contigs and a 3-fold increase in the N 50 value compared with the previous Illumina-only assembly.

Fulltext Whole genome sequencing and analysis reveal insights into the genetic structure, diversity and evolutionary relatedness of luxI and luxR homologs in bacteria belonging to the Sphingomonadaceae family

Gan HM, Gan HY, Ahmad NH, Aziz NA, Hudson AO, Savka MA

Front Cell Infect Microbiol, 2014;4:188.

PMID: 25621282 DOI: 10.3389/fcimb.2014.00188

Here we report the draft genomes and annotation of four N-acyl homoserine lactone (AHL)-producing members from the family Sphingomonadaceae. Comparative genomic analyses of 62 Sphingomonadaceae genomes were performed to gain insights into the distribution of the canonical luxI/R-type quorum sensing (QS) network within this family. Forty genomes contained at least one luxR homolog while the genome of Sphingobium yanoikuyae B1 contained seven Open Reading Frames (ORFs) that have significant homology to that of luxR. Thirty-three genomes contained at least one luxI homolog while the genomes of Sphingobium sp. SYK6, Sphingobium japonicum, and Sphingobium lactosutens contained four luxI. Using phylogenetic analysis, the sphingomonad LuxR homologs formed five distinct clades with two minor clades located near the plant associated bacteria (PAB) LuxR solo clade. This work for the first time shows that 13 Sphingobium and one Sphingomonas genome(s) contain three convergently oriented genes composed of two tandem luxR genes proximal to one luxI (luxR-luxR-luxI). Interestingly, luxI solos were identified in two Sphingobium species and may represent species that contribute to AHL-based QS system by contributing AHL molecules but are unable to perceive AHLs as signals. This work provides the most comprehensive description of the luxI/R circuitry and genome-based taxonomical description of the available sphingomonad genomes to date indicating that the presence of luxR solos and luxI solos are not an uncommon feature in members of the Sphingomonadaceae family.

Fulltext Whole-Genome Sequences of Five Oligotrophic Bacteria Isolated from Deep within Lechuguilla Cave, New Mexico

Gan HY, Gan HM, Tarasco AM, Busairi NI, Barton HA, Hudson AO, et al.

Genome Announc, 2014;2(6).

PMID: 25377711 DOI: 10.1128/genomeA.01133-14

Here, we report the whole-genome sequences and annotation of five oligotrophic bacteria from two sites within the Lechuguilla Cave in the Carlsbad Caverns National Park, NM. Three of the five genomes contain an acyl-homoserine lactone signal synthase ortholog (luxI) that is involved in cell-to-cell communication via quorum sensing.

Fulltext L,L-diaminopimelate aminotransferase (DapL): a putative target for the development of narrow-spectrum antibacterial compounds

Triassi AJ, Wheatley MS, Savka MA, Gan HM, Dobson RC, Hudson AO

Front Microbiol, 2014;5:509.

PMID: 25309529 DOI: 10.3389/fmicb.2014.00509

Despite the urgent need for sustained development of novel antibacterial compounds to combat the drastic rise in antibiotic resistant and emerging bacterial infections, only a few clinically relevant antibacterial drugs have been recently developed. One of the bottlenecks impeding the development of novel antibacterial compounds is the identification of new enzymatic targets. The nutritionally essential amino acid anabolic pathways, for example lysine biosynthesis, provide an opportunity to explore the development of antibacterial compounds, since human genomes do not possess the genes necessary to synthesize these amino acids de novo. The diaminopimelate (DAP)/lysine (lys) anabolic pathways are attractive targets for antibacterial development since the penultimate lys precursor meso-DAP (m-DAP) is a cross-linking amino acid in the peptidoglycan (PG) cell wall of most Gram-negative bacteria and lys plays a similar role in the PG of most Gram-positive bacteria, in addition to its role as one of the 20 proteogenic amino acids. The L,L-diaminopimelate aminotransferase (DapL) pathway was recently identified as a novel variant of the DAP/lys anabolic pathways. The DapL pathway has been identified in the pathogenic bacteria belonging to the genus; Chlamydia, Leptospira, and Treponema. The dapL gene has been identified in the genomes of 381 or approximately 13% of the 2771 bacteria that have been sequenced, annotated and reposited in the NCBI database, as of May 23, 2014. The narrow distribution of the DapL pathway in the bacterial domain provides an opportunity for the development and or discovery of narrow spectrum antibacterial compounds.

Fulltext High-Quality Draft Whole-Genome Sequences of Three Strains of Enterobacter Isolated from Jamaican Dioscorea cayenensis (Yellow Yam)

Gan HM, Triassi AJ, Wheatley MS, Savka MA, Hudson AO

Genome Announc, 2014;2(2).

PMID: 24625871 DOI: 10.1128/genomeA.00170-14

Here we report the whole-genome sequences of three endophytic bacteria, Enterobacter sp. strain DC1, Enterobacter sp. strain DC3, and Enterobacter sp. strain DC4, from root tubers of the yellow yam plant, Dioscorea cayenensis. Preliminary analyses suggest that the genomes of the three bacteria contain genes involved in acetoin and indole-3-acetic acid metabolism.

Fulltext Comparative genomic analysis of six bacteria belonging to the genus Novosphingobium: insights into marine adaptation, cell-cell signaling and bioremediation

Gan HM, Hudson AO, Rahman AY, Chan KG, Savka MA

BMC Genomics, 2013;14:431.

PMID: 23809012 DOI: 10.1186/1471-2164-14-431

Bacteria belonging to the genus Novosphingobium are known to be metabolically versatile and occupy different ecological niches. In the absence of genomic data and/or analysis, knowledge of the bacteria that belong to this genus is currently limited to biochemical characteristics. In this study, we analyzed the whole genome sequencing data of six bacteria in the Novosphingobium genus and provide evidence to show the presence of genes that are associated with salt tolerance, cell-cell signaling and aromatic compound biodegradation phenotypes. Additionally, we show the taxonomic relationship between the sequenced bacteria based on phylogenomic analysis, average amino acid identity (AAI) and genomic signatures.

Fulltext Whole-Genome Sequencing of Pantoea sp. Strain RIT388, a Potential Oral Opportunistic Pathogen Isolated from a Chewing Stick (Distemonanthus benthamianus)

Gan HM, Parthasarathy A, Henry KR, Savka MA, Thomas BN, Hudson AO

Microbiol Resour Announc, 2020 Feb 27;9(9).

PMID: 32107300 DOI: 10.1128/MRA.01468-19

In this study, we report the isolation, identification, characterization, and whole-genome sequence of the endophyte Pantoea sp. strain RIT388, isolated from Distemonanthus benthamianus, a plant known for its antifungal and antibacterial properties that is commonly used for chewing sticks.

Fulltext Whole-genome sequence of Enterobacter sp. strain SST3, an endophyte isolated from Jamaican sugarcane (Saccharum sp.) stalk tissue

Gan HM, McGroty SE, Chew TH, Chan KG, Buckley LJ, Savka MA, et al.

J Bacteriol, 2012 Nov;194(21):5981-2.

PMID: 23045495 DOI: 10.1128/JB.01469-12

Enterobacter sp. strain SST3 is an endophytic bacterium isolated from Saccharum spp. Here we present its annotated draft genome that may shed light on its role as a bacterial endophyte of sugarcane. To our knowledge, this is the first genome announcement of a sugarcane-associated bacterium from the genus Enterobacter.

Fulltext Genomic characterization of bacteria from the ultra-oligotrophic Madison aquifer: insight into the archetypical LuxI/LuxR and identification of novel LuxR solos

Wengert PC, Wong NH, Barton HA, Gan HM, Hudson AO, Savka MA

BMC Res Notes, 2021 May 08;14(1):175.

PMID: 33964980 DOI: 10.1186/s13104-021-05589-6

OBJECTIVES: To characterize the bacterial community of Wind Cave's Madison aquifer through whole-genome sequencing, and to better understand the bacterial ecology by identifying genes involved in acyl-homoserine lactone (AHL) based quorum-sensing (QS) systems.

RESULTS: Genome-based taxonomic classification revealed the microbial richness present in the pristine Madison aquifer. The strains were found to span eleven genera and fourteen species, of which eight had uncertain taxonomic classifications. The genomes of strains SD129 and SD340 were found to contain the archetypical AHL QS system composed of two genes, luxI and luxR. Surprisingly, the genomes of strains SD115, SD129, SD274 and SD316 were found to contain one to three luxR orphans (solos). Strain SD129, besides possessing an archetypical AHL QS luxI-luxR pair, also contained two luxR solos, while strain SD316 contained three LuxR solos and no luxI-luxR pairs. The ligand-binding domain of two LuxR solos, one each from strains SD129 and SD316, were found to contain novel substitutions not previously reported, thus may represent two LuxR orphans that detection and response to unknown self-produced signal(s), or to signal(s) produced by other organisms.

Fulltext Insight into the resistome and quorum sensing system of a divergent Acinetobacter pittii isolate from an untouched site of the Lechuguilla Cave

Gan HM, Wengert P, Barton HA, Hudson AO, Savka MA

Access Microbiol, 2020;2(2):acmi000089.

PMID: 34568753 DOI: 10.1099/acmi.0.000089

Acinetobacter are Gram-negative bacteria belonging to the sub-phyla Gammaproteobacteria, commonly associated with soils, animal feeds and water. Some members of the Acinetobacter have been implicated in hospital-acquired infections, with broad-spectrum antibiotic resistance. Here we report the whole-genome sequence of LC510, an Acinetobacter species isolated from deep within a pristine location of the Lechuguilla Cave. Pairwise nucleotide comparison to three type strains within the genus Acinetobacter assigned LC510 as an Acinetobacter pittii isolate. Scanning of the LC510 genome identified two genes coding for b-lactamase resistance, despite the fact that LC510 was isolated from a portion of the cave not previously visited by humans and protected from anthropogenic input. The ability to produce acyl-homoserine lactone (AHL) signal in culture medium, an observation that is consistent with the identification of the luxI and luxR homologues in its genome, suggests that cell-to-cell communication remains important in an isolated cave ecosystem.

Genome sequencing-assisted identification and the first functional validation of N-acyl-homoserine-lactone synthases from the Sphingomonadaceae family

Gan HM, Dailey LK, Halliday N, Williams P, Hudson AO, Savka MA

PeerJ, 2016;4:e2332.

PMID: 27635318 DOI: 10.7717/peerj.2332

Members of the genus Novosphingobium have been isolated from a variety of environmental niches. Although genomics analyses have suggested the presence of genes associated with quorum sensing signal production e.g., the N-acyl-homoserine lactone (AHL) synthase (luxI) homologs in various Novosphingobium species, to date, no luxI homologs have been experimentally validated.

Fulltext Whole genome sequencing of Rhodotorula mucilaginosa isolated from the chewing stick (Distemonanthus benthamianus): insights into Rhodotorula phylogeny, mitogenome dynamics and carotenoid biosynthesis

Gan HM, Thomas BN, Cavanaugh NT, Morales GH, Mayers AN, Savka MA, et al.

PeerJ, 2017;5:e4030.

PMID: 29158974 DOI: 10.7717/peerj.4030

In industry, the yeast Rhodotorula mucilaginosa is commonly used for the production of carotenoids. The production of carotenoids is important because they are used as natural colorants in food and some carotenoids are precursors of retinol (vitamin A). However, the identification and molecular characterization of the carotenoid pathway/s in species belonging to the genus Rhodotorula is scarce due to the lack of genomic information thus potentially impeding effective metabolic engineering of these yeast strains for improved carotenoid production. In this study, we report the isolation, identification, characterization and the whole nuclear genome and mitogenome sequence of the endophyte R. mucilaginosa RIT389 isolated from Distemonanthus benthamianus, a plant known for its anti-fungal and antibacterial properties and commonly used as chewing sticks. The assembled genome of R. mucilaginosa RIT389 is 19 Mbp in length with an estimated genomic heterozygosity of 9.29%. Whole genome phylogeny supports the species designation of strain RIT389 within the genus in addition to supporting the monophyly of the currently sequenced Rhodotorula species. Further, we report for the first time, the recovery of the complete mitochondrial genome of R. mucilaginosa using the genome skimming approach. The assembled mitogenome is at least 7,000 bases larger than that of Rhodotorula taiwanensis which is largely attributed to the presence of large intronic regions containing open reading frames coding for homing endonuclease from the LAGLIDADG and GIY-YIG families. Furthermore, genomic regions containing the key genes for carotenoid production were identified in R. mucilaginosa RIT389, revealing differences in gene synteny that may play a role in the regulation of the biotechnologically important carotenoid synthesis pathways in yeasts.

Fulltext Whole-Genome Sequence of Endophytic Bacteria Associated with Poison Ivy Vine (Toxicodendron radicans)

Gan HM, Penix TS, Wengert PC, Wong NH, Hudson AO, Kumar G, et al.

Microbiol Resour Announc, 2023 Apr 18;12(4):e0123222.

PMID: 36920211 DOI: 10.1128/mra.01232-22

Here, we report the genome assemblies of 11 endophytic bacteria, isolated from poison ivy vine (Toxicodendron radicans). Five species belonging to the genus Pseudomonas, two species of Curtobacterium, one strain of Pantoea agglomerans, and one species from the Bacillus, Cellulomonas, and Enterobacter genera were isolated from the interior tissue of poison ivy.

Endophytic bacteria associated with wild-type banana seed (Musa balbisiana): whole genome sequencing

Kumar G, Gan HM, Popielarz H, Steele J, Parthasarathy A, Hudson AO, et al.

Microbiol Resour Announc, 2023 Nov 03.

PMID: 37921458 DOI: 10.1128/MRA.00650-23

We present the whole-genome sequences of five endophytic bacteria isolated from Musa balbisiana seeds. These strains represent five different genera: Bacillus, Brachybacterium, Enterobacter, Enterococcus, and Pantoea. Among these, three genera (Bacillus, Pantoea, and Enterobacter) were previously recognized for their antagonistic effects against Fusarium wilt, a highly destructive disease that affects banana plants.

Fulltext Whole-genome sequencing of four culturable endophytic bacteria from German hardneck garlic cloves (Allium sativum L.)

Kumar G, Gan HM, Wengert P, Penix T, Parthasarathy A, Hudson AO, et al.

Microbiol Resour Announc, 2024 Apr 11;13(4):e0122523.

PMID: 38470029 DOI: 10.1128/mra.01225-23

We present the whole-genome sequence of four bacterial endophytes associated with German hardneck garlic cloves (Allium sativum L.). Among them, Agrobacterium fabrum and Pantoea agglomerans are associated with plant protection, while Rahnella perminowiae and Stenotrophomonas lactitubi are pathogens. These data will facilitate the identification of genes to improve garlic.

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